Transport and transfer device

ABSTRACT

Disclosed is a workpiece conveyor and delivery device for a vacuum processing plant. Workpieces are delivered from one device to another, both devices being located opposite each other and moving in relation to each other. A controllable magnet arrangement is provided on one of the devices. A moveable armature element acts as a holding device for the workpiece on one of the two devices which move in relation to each other, namely the device provided with the magnet arrangement. Magnet arrangement is driven to activate the holding device which can be deactivated for delivery of workpiece.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT Application No. PCT/CH97/00344filed on Sep. 17, 1997.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a transport and transfer device.

A device of this type is known from EP-0 591 706. A workpiece in theform of a disc is fixed in a star-shaped transport arrangement byclamping it between a permanent magnet on the device and an armaturepiece.

In a transfer area to an additional transport device the armature islifted off its seat, against the force of the permanent magnet, undercontrol of an electromagnet so that the disc-shaped workpiece isreleased for transfer by means of a mechanically actuated holder on theadditional transport device.

Conversely, that is, for transfer in the opposite direction, thearmature is released by the electromagnet and placed on the workpiececlamped by a mechanically actuated holder so that it is picked up at thereceiving transport device by the force of the permanent magnet. Theworkpiece is then released to the receiving transport device by themechanically actuated holder.

The disadvantage of this design is that there is a mechanically actuatedand controlled arrangement on the one device. In addition to the complexdesign the mechanical movements are problematic under vacuum conditions:It promotes particle formation which leads to higher workpiece rejectrates. The greater the number of mechanically moved parts in the vacuumatmosphere the greater the potential for faults in the process executionwhich consequently impairs the reliability of the equipment. In additionthis mechanical holder increases the cycle time of the overall systemwhich ultimately increases the manufacturing and operating costs of thesystem and thereby the costs for the processed workpieces.

The objective of this invention is to eliminate the disadvantages of adevice of the aforementioned type.

This is achieved in accordance with the present invention by fittingboth arrangements which are movable relative to each other with at leastone magnet, each as part of the controllable magnet arrangement, and byhaving said magnet with the armature part forming a workpiece holder inboth arrangements, and by controlling the magnet arrangement in thetransfer area in such a way that the armature of one or the otherarrangement becomes holding, a device without any mechanical joints,meshing parts, etc. is achieved. This significantly improves thereliability of the device. The transfer cycle time can be significantlyreduced, preferably by more than 25%, for example, as in the case of thesubsequently described device, from the usual 10 sec. to less than 7.5sec. This results in significant cost reductions, on the one hand due tothe simplicity of the design, in the manufacture of a correspondingsystem, as well as in the operating costs and consequently theproduction costs of the workpieces treated by the system.

If workpieces, and in particular disc-shaped workpieces such asmini-disks, compact disks, hard disks, MO disks or semiconductor wafersare to be surface-masked before treatment in the system with a deviceaccording to the invention, at least one of the armature parts issimultaneously used as a masking element so that the holder, transferfunction and masking can be optimally combined. In this way theaforementioned advantages can be even better realized.

The preferred designs of the device according to the invention, theirimplementation on a vacuum chamber or a vacuum treatment system as wellas the basic transport and transfer techniques according to theinvention, and the preferred utilization, are described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is subsequently explained by means of illustrations.Illustrated are:

FIG. 1 is a schematic representation of the basic operating principle ofthe device according to the invention;

FIG. 2 is a schematic longitudinal cross-section of a preferred designversion of the device according to the invention;

FIG. 3 Another design of the invention based on the representation inFIG. 2;

FIG. 4 Exploded view of a preferred armature design for handling adisc-shaped workpiece with center hole.

FIG. 5 is a schematic diagram of a treatment system with implementationof the device according to the invention and the functional units of thesystem;

FIG. 6 is a simplified perspective view showing the primary functionalprocess elements of the system illustrated in FIG. 5;

FIG. 7a is a chamber according to the invention on the system accordingto FIG. 5 or 6, with the device according to the invention shown in thereceiving/transfer position;

FIG. 7b is a Chamber according to 7 a with the device in the transportposition;

FIG. 8 is a schematic enlarged view of the device according to theinvention in the transfer/receiving position according to FIG. 7a;

FIGS. 9a and 9 b are a schematic view and top view of a part of thesystem according to FIG. 6 in the transport position (a) and in thetreatment or receiving/transfer position (b).

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 schematically shows a transport arrangement 1 which, as indicatedby the double arrow T, is driven inside a vacuum chamber (notillustrated).

Along its movement path a holder 3 for workpiece 5 is positioned intransfer area B opposite another arrangement 7 with a holder 9. Thearrangement 7 can either be stationary or also a transport device.

Both arrangements 1 and 7 have at least one magnet element 11 or 13respectively. In addition a follower armature 15 is provided as aseparate part for a workpiece 5 which is schematically represented as adisc with a center hole. The follower armature consists at leastpartially of magnetic material. When the workpiece 5 and the followerarmature 15 rest on the transport arrangement 1 as shown by the dashedline at 15 a, workpiece 5 is held in place by follower armature 15 dueto the interaction of magnet arrangement 13 with the follower armature15. If (not shown) workpiece 5 and the follower armature rest on thetransport arrangement 7, the follower armature 15 also holds theworkpiece 5 in place due to the interaction between the magnetarrangement 11 and the follower armature 15.

In transfer area B the magnet arrangements 11 and 13 are at least partof a controllable magnet arrangement. Under the most general aspect ofthe present invention the controllable magnet arrangement can beimplemented by designing one and/or the other magnet arrangement 11 or13 as an electromagnet; in an especially preferred design version themagnet arrangements 11 and 13 are designed as permanent magnets. Theentire device according to the invention is then based on theutilization of permanent magnets according to FIG. 1. However, themagnets can also be attached to armature 15 with the stationary parts ofthe device consequently being made of magnetic material.

For transferring workpiece 5 away from arrangement 1 to arrangement 7,the permanent magnet arrangement 11 must overcome the retention force ofthe permanent magnet arrangement 13. According to this invention this issolved in such a way that magnet arrangement 11 is designed with astronger magnetic force than magnet arrangement 13. With the followerarmature 15 in position 15 a the permanent magnet arrangement 11represented by dash-dotted lines in position 11 a, is advanced by drive12 toward the receiving element 3 and picks up the follower armature 15against the retention force of magnet arrangement 13. Preferred on thearmature are detachable fixing elements 17, for example, springy clips,detents such as spring-loaded balls that fix workpiece 5 to the followerarmature 15. Together with the follower armature 15 also workpiece 5 ispicked up by magnet arrangement 11 and returned to receiving holder 9.

For returning workpiece 5 and the follower armature 15 from arrangement7 to arrangement 1, magnet arrangement 11 is basically retracted toposition 11 b shown with dashed lines, or magnet arrangement 13 ispushed forward against the follower armature 15 (not shown) until theretention force of magnet arrangement 13 again dominates.

The described principle is consequently based on connecting theworkpiece separably with the follower armature and to shuttle the latterbetween a permanent magnet on the one arrangement and a permanent magneton the other arrangement where the magnetic force is controlled byvarying the distance of the receiving magnet relative to thetransferring magnet.

An additional, very important advantage of the procedure according tothis invention is that no additional transport vehicle needs to beprovided for the workpiece, neither for the transfer nor for thetransport at one or both arrangements 7 or 1.

FIG. 2 schematically shows a preferred design version of the presentinvention. This arrangement is designed for handling disc-shapedworkpieces with a center hole which before treatment in the vacuumsystem, such as in a coating application, need to be masked in theircenter area as well as the peripheral area.

On the one arrangement 20, as shown with the double arrow Tcorresponding to a transport arrangement, a holding surface 23 forworkpiece 25 is provided. In the center of holding surface 23 a blindhole 27 is provided on the base on which a permanent magnet 29 isinstalled. Workpiece 25 is deposited on holding surface 23 where it isclamped by the magnetic follower armature 31 designed as a central mask.The periphery of workpiece 25 is clamped to transport arrangement 20 bymasking ring 33 equipped with peripheral magnets 35 that also functionsas an armature.

The central follower armature 31 holds the workpiece 25 by means ofspring clips 37. Spring-loaded balls can be used in place of springclips.

The second arrangement 40 comprises a cylinder 42 with a terminationplate 43 that forms a holding surface 44. A piston 46 glides within thecylinder space of cylinder 42. Permanent magnets 50 and 52 are installedat a central protrusion 48 and a peripheral ring protrusion 49. Throughthe movement s of piston 46 and appropriate recesses in terminationplate 43 of cylinder 42 the magnets 50 and 52 are positioned immediatelyinto the area of surface 44 or retracted from the latter as illustrated.Arrangement 40 is also a transport arrangement in which cylinder 42 isthe end of a transport plunger arrangement, T40. A plunger piston 54glides inside cylinder space 56 which is installed together with a drivecylinder space 57 for a piston 58 and piston 46 in housing 60.

Magnets 52 and 50 are preferably stronger than magnets 35 and 29.

For transferring workpiece 25 from the illustrated position onarrangement 20 to arrangement 40, the entire cylinder 42 is movedforward against workpiece 25 and armature 33 or 31 by means of thepiston/cylinder arrangement 54/60 with piston 46 in the illustratedforward position, until the force of magnets 50, 52 is sufficient todraw the armatures 33, 31 together with workpiece 25 to surface 44. Theworkpiece, held by armatures 31/33 can then be transported byarrangement 40.

Conversely, for returning workpiece 25 with armatures 33/31 to thearrangement 20, piston 46 and magnets 50, 52 are retracted from theposition shown in FIG. 2 by means of the piston/cylinder arrangementuntil the force of magnets 35/29 overcomes the retention force of theretracted magnets 50/52. After the transfer the transport can continuewith arrangement 20.

In this way a very simple transport and transfer device is created thatis based solely of the effect of preferably permanent magnets whoseinteraction with the magnetic follower and fixing armature for theworkpiece is controlled by the corresponding effective distances.

Of course, it is also possible to design one of the two arrangements 40or 20 illustrated in FIG. 2, preferably arrangement 20, as a stationarydevice, for example, as a feeding-opening area for a treatment chamber.In this case the holding and masking armatures 33 or 31 are, of course,reversed, as shown schematically at 31 a with dashed lines, and inparticular the central area of surface 44 and piston 46 are designed toaccommodate the central prolongation of central mask 31. Thisconstellation is schematically illustrated in FIG. 3. In view of whathas been said so far, no further information is needed. The processingeffect is schematically shown with Q.

When several armature elements are used as shown, for example, in FIG.1, 2, or 3, one and/or the other armature can be fitted with holdingdevices in the form of spring clips or ball detents illustrated at 17 inFIG. 1, depending on the design.

The procedure according to the invention achieves not only an eleganttransport and transfer technique as described further above, but as hasbeen demonstrated additional masking steps in the system are avoided andas has been mentioned eliminates the need for an additional transportvehicle that “accompanies” a workpiece such as the aforementioned disksthrough the system. This increases the reliability of the system, andthe cycle times are shortened by at least 25% in comparison with systemsin which a separate masking step is necessary.

FIG. 4 is an exploded view of a preferred design of the followerarmatures 41 and 43 with respect to a workpiece 45. On the centralfollower armature 43 at least one ball detent 47 is provided as a holderfor workpiece 45. A permanent magnet 49 that is part arranged on thefollower armature 43 is part of the magnetically active material.

FIG. 5 shows a system with transport and transfer device according tothe invention. Illustrated are:

51: Belt conveyor for the workpiece discs 52;

53: Transport robot;

55: Two-armed transport arrangement in a vacuum chamber (not shown),pivotable around its axis as shown in S₅₅, where parts of the transportand transfer device according to the invention are mounted on both armsdesigned as plungers;

57: A loading station for the follower armatures according to theinvention which are inserted into the transport arms of transportarrangement 55 through a corresponding opening in the vacuum chamber(not illustrated);

59: A load lock chamber;

61: A main transport chamber of the system with several process chambers63.

FIG. 6 shows process chambers 63, one of which is open. They are flangedto a main transport chamber 61. In the main transport chamber 61 arotary transport star 65 is provided with a number of plungers, each ofwhich is equipped with elements for transport and transfer in accordancewith the invention. Through an opening the workpiece discs are shuttledby the two-armed transport arrangement 55 in the direction of the arrowas shown in FIG. 4 by means of the armatures 41 or 43 which function asmasks. arrows as shown in FIG. 4 by means of the armatures 41 or 43which function as masks.

FIG. 7a shows the two-armed transport arrangement 55 in thecorresponding transport chamber 71 as it interacts with the maintransport chamber 61. At the transfer opening 73 a load lock 59 isintegrated, possibly also one on opening 74. In accordance with theposition of FIG. 7a and with respect to FIG. 2 the transport plungers 42are extended and together with the corresponding openings in chamber 71constitute a seal. Pistons 46 are also extended and together with thecorresponding magnets 50, 52 (not shown in FIG. 7) fix the workpiecediscs and their follower armatures (not shown here). In this positionthe transport arrangement cannot be pivoted but is locked in thetransfer/receiving position. With the one illustrated plunger oftransport arrangement 65 in the main transport chamber 61 a workpiecewith the corresponding follower armatures is picked up from or returnedto transport arrangement 55.

The same applies with respect to the pick-up or transfer of a workpieceat the second chamber opening 74. As can be seen in the transfer area tothe main transport chamber 61, both plungers acting on this opening withthe corresponding opening edge function as a seal in such a way that theopening itself, through the thickness of its wall, functions as a lockchamber. The lock valves are implemented through the correspondingplungers.

When pistons 46 are still extended as shown in FIG. 7b, plungers 42 areretracted so that arrangement 55 is in the pivotable transport position.

In FIG. 8 the two plungers on transport arrangement 55 according to FIG.7 are shown in more detail. Both plungers are extended and seal at thecorresponding opening edges. As indicated by arrow S₄₆₁ the left-handpiston is retracted momentarily in conjunction with a plunger of themain transport arrangement 61 which means that workpiece 52 with thecorresponding follower and masking armatures 41, 43 shown in FIG. 4 aretransferred to the plunger on the main chamber side. At the same timepiston 46 on the right-hand plunger is extended as shown by arrow S₄₆₂and picks up a workpiece 52 with the corresponding follower armatures 41or 43 functioning as masks.

As can be seen from FIGS. 7 and 8, the forward movements of pistons 46provided at several plungers of a transport arrangement, can becontrolled independently of each other which may be desirable also forthe movement of plungers 42.

FIG. 9 schematically shows the transport position (a) of the plungers onthe main transport arrangement 65 according to FIG. 6 as well as in thetreatment position or transfer position according to diagram (b). Byobserving FIG. 9b the flow-through cycle for workpieces becomesapparent:

In A an untreated workpiece is picked up from 55;

In B a treated workpiece is transferred from 61 to 55;

55 is pivoted;

Said treated workpiece is output at A and at B the treated workpiece istransferred to 61, 61 is pivoted further.

As can be seen on the right-hand side of FIG. 8 the workpiece discs inposition A can be further transported without being accompanied by themasking and follower armatures. Looking back at FIG. 9 these passthrough the treatment cycles of the workpieces several times and arereplaced at arrangement 91 only as required and after relatively manytreatment cycles for which A purpose transport arrangement 55 is pivotedinto the intermediate position shown in FIG. 9b with dash-dotted lines.

What is claimed is:
 1. A method for manufacturing storage disks orsemiconductor wafer workpieces, comprising: releasably filing a transferarmature member comprising magnetic material to a respective workpiece,magnetically attracting said transfer armature member with saidworkpiece fixed thereto towards and onto a first transport arrangement,moving said first transport arrangement with said transfer armaturemember and said workpiece magnetically attracted thereto towards andinto a transfer position, magnetically attracting in said transferposition said transfer armature member with said workpiece from said onetransport arrangement towards and onto a further transport arrangement,moving said further transport arrangement with said transfer armaturemember and said workpiece magnetically attracted thereto towards atreatment station, moving said further transport arrangement with saidtransfer armature member and said workpiece magnetically attractedthereto from said treatment station towards and into a further transferpositions and magnetically attracting at said further transfer positionsaid transfer armature member with said workpiece from said furthertransport arrangement towards and onto a still further transport member.2. The method of claim 1, wherein said still further transport member issaid one transport member and said one transfer position is said furthertransfer position.
 3. The method of claim 1, further comprising the stepof providing said workpiece in a disk-shaped configuration having acentral hole with said transfer armature member through said centralhole.
 4. The method of claim 1, wherein said workpiece is ofnon-magnetic material.
 5. The method of claim 1, wherein said workpieceis one of a mini disk, a compact disk and a hard disk.
 6. A method formanufacturing storage disks or semiconductor wafer workpieces accordingto claim 1, wherein said still further transport arrangement is formedby said first transport arrangement, and said further transfer positionis formed by said one transfer position.